Magnetic recording materials such as magnetic tapes and disks normally consist of a plastic support on which is formed a magnetic layer which can be a metallic layer or ferromagnetic particles dispersed in a binder resin. Over the magnetic layer a polymeric protective layer usually is formed. A wide range of polymers have been used or proposed for the protective layer.
Desirably, the protective layer has a low coefficient of friction in order that the magnetic head will have a minimum of resistance and will not be abraded when in contact with the magnetic recording element. The protective layer should also provide a moisture barrier and protect the magnetic layer against corrosion, a problem of particular importance with certain magnetic materials such as CoNi compositions, at high humidity. The protective layer should be physically tough in order to resist wear and transfer to the head when in contact with the magnetic head and to resist scratching and other physical damage. The protective layer should have these useful qualities, even though formed as a very thin layer, for the spacing between the magnetic layer and the head should be kept to a minimum.
Unfortunately, none of the presently used protective layers provide all of these qualities in the desired degree. Some are too high in coefficient of friction. Others do not provide an adequate moisture barrier to protect against corrosion and others are not tough enough for long wear.
A need has existed for a magnetic recording element having a protective layer which has, in a high degree, all of the desired qualities of low coefficient of friction, corrosion protection and toughness. In accordance with the present invention, a magnetic recording element is provided which has a protective layer having the desired qualities in a desirably high degree.